Book Review

Histology of the Nervous System of Man and Vertebrates

N Engl J Med 1995; 333:1088October 19, 1995

Article

Histology of the Nervous System of Man and Vertebrates
(History of Neuroscience. No. 7.) By Santiago Ramón y Cajal. 1611 pp. in two volumes, illustrated. New York, Oxford University Press, 1995. $195. ISBN: 0-19-507401-7

In the dynamic world of cellular neuroscience today, dominated as it is by single-channel kinetics and molecular neurobiology, the very word “histology” seems dry and static. Yet this new translation of the classic work by Santiago Ramón y Cajal is a poignant reminder that histology need not be dull.

In the late 19th century, many prominent investigators believed that the central nervous system was a syncytium or network of nerve cells (the reticular theory). The concept of the neuron doctrine — which postulated distinct neurons with axons, dendrites, and discrete connections — although it had proponents, was not yet well established. In 1873, Camillo Golgi developed his silver-staining techniques that allowed the staining of a neuron cell body and all its processes in its entirety. Even more important was the selectivity of the stain; only about 1 in 100 neurons was stained. It remained for Cajal, who began using these techniques extensively in 1888, to realize the true potential of this method. To Cajal, the selectivity of the method allowed him to sort out the “tangled thicket” of neurons, the “bee-hive of cells” previously studied with unselective staining methods. The Golgi stain was his probe of neuronal structure and function and the key to establishing the neuron doctrine. With this technique, Cajal proceeded to investigate the various regions of the central nervous system, paying particular attention to the organization of the retina, cerebellum, and spinal cord in humans and other vertebrates (including embryos). Ironically, Golgi (with whom Cajal shared the Nobel prize in 1906) continued to adhere to the reticular theory even into the 20th century.

This magnum opus represents a summary of 20 years of research by Cajal. Yet, rather than a mere description of structural relations, this work is a magnificent formulation of theories of interactions and interrelations. It presents the concepts and discusses the dynamics of axons, dendrites, growth cones, and connectivity. When reading the chapters, profusely illustrated by over 1000 meticulous drawings of observations by Cajal, the reader is always aware of the excitement of their implications. Throughout the various chapters, Cajal stresses function even more than structure. Often a paragraph begins with a question addressing the possible importance of the structural relationships. Cajal's development of the concept of the neuron doctrine has been compared to William Harvey's contributions to our understanding of blood circulation, and Histology of the Nervous System has been compared in importance to Darwin's Origin of the Species. Both are apt comparisons. Obviously, considerable progress has been made since these original observations by Cajal. Although some of the terminology has changed and some concepts of connectivity have been modified (e.g., not all synapses are axodendritic), in large part the observations and treatises put forth are remarkably relevant today.

Gordon Sheppard in his 1991 monograph recognizes Cajal as the chief architect of the neuron doctrine and laments the fact that the “monumental” Histologie du Système Nerveux de l'Homme et des Vertébrés (the French translation) was not available in English at that time, mentioning it as an “indispensable starting point for cellular studies of the nervous system.” Although translated into French in 1909 and 1911, not until this edition has the work been available in English. This masterly translation by Swanson and Swanson from the later French edition seems to preserve the spirit and spark of the earlier editions. Purists may be concerned that too much may have been lost in the double passage from Spanish to French to English, but the French translation by L. Azoulay is regarded as the definitive edition and indeed was done in close cooperation with Cajal and included new material and organization. The volumes themselves are beautifully produced and faithfully illustrated. Clinical neurologists, neurosurgeons, and psychiatrists will enjoy and benefit from reviewing and reading this work, but perhaps every cellular or molecular neuroscientist should be required to read this classic. I welcome its accessibility in this new translation and can only wish that an English translation had been available sooner as a model for the authors of my medical school histology textbooks.

Gregory K. Bergey, M.D.
University of Maryland School of Medicine, Baltimore, MD 21201